Mask-harness tension compensating device



Feb. 7,1961 H. W.SEELER MASK-HARNESS TENSION COMPENSATING DEVICE FiledMay 6, 1957 2,970,593. MASK-HARNESS TENSION COMPENSATING DEVICE Henry W.Seeler, Dayton, Ohio, assignor to the United States of America asrepresented by the Secretary of the Air Force Filed May 6, 1957, Ser.No. 657,461 4 Claims. (Cl. 128-142) (Granted under Title 35, US. Code(1952), see. 266) The invention described herein may be manufactured andused by or for the United States Government for governmental purposeswithout payment to me of any royalty thereon.

This invention relates to a device for regulating the tension of theharness connecting a breathing mask to a headgear and, moreparticularly, to a device that automatically regulates the tension ofthe harness connecting the breathing mask to the headgear in accordancewith the ambient pressure.

In connecting a high altitude oxygen breathing mask to a headgear by aharness, it is necessary to adjust the tension of the harness at groundlevel so that the mask is leak proof not only at demand breathing, butalso at pressure breathing up to fourteen inches of water, the latercondition existing at high altitudes. The harness tension, which isrequired to insure that there is no leakage about the mask at highaltitude, is sufiiciently large that it creates an uncomfortablemechanical pres: sure around the face of the wearer and especially inthe nose area.

One method of alleviating this problem of an uncom fortable fit of themask against the face of the wearer when large harness tensions are notrequired it to use a manual adjustment of the harness connection to themask. This has the problem of requiring a manual actuation; the highspeed of jet aircraft, for example, requires such constant attention ofthe pilot that even the slight diversion to manually adjust themechanism may create an accident hazard. This manual adjustment also hasonly one variation in the tension of the mask harness whereby a greatertension of the harness is employed before it is needed to seal the maskagainst the face of the wearer.

The present invention satisfactorily solves these problems by requiringonly a small harness tension at ground level to make the mask leak proofduring demand breathing. While this small harness tension furnishes theseal during demand breathing, only a slight pressure exists on thewearers face so that the mask is substantially comfortable. As theaircraft gains altitude, the present invention increases the harnesstension in response to the decrease in ambient air pressure. Thisresults in the mask tightening against the wearers face as the altitudeincreases, but it does not increase the pressure of the mask against thewearers face substantially beyond that required to insure a seal betweenthe mask and the wearers face. When very high altitudes are encountered,the harness tension is increased further so that a large pressure iscreated by the mask against the wearers face to thereby seal duringpressure breathing at large vacuums. However, as soon as the altitudedecreases, the harness tension reduces accordingly.

An object of this invention is to provide a device for automaticallyadjusting the tension of the harness ofa breathing mask according to theambient altitude.

Another object of this invention is to provide a device thatincreasesthe force holding the breathing mask against the face of the wearer asthe ambient pressure decreases.

Other objects of this invention will be readily perceived from thefollowing description.

ited States Patent Too ments of the invention in which Fig. 1 is anelevational view, partly in section, of the compensating device of thepresent invention employed with a breathing mask;

Fig. 2 is a fragmentary view, similar to Fig. 1, of another form of thepresent invention; and

Fig. 3 is an elevational view, partly in section, of another type ofcompensating device.

Referring to the drawing and particularly Fig, 1, there is shown anoxygen breathing mask 10 connected to a headgear 11 such as a hard shellhelmet, for example, by harness straps 12. The headgear 11 may be a softhelmet, a headset, or a net helmet, if desired. It is only necessarythat the headgear be joined to the harness straps 12 to support the mask10. The harness straps 12 are joined to the headgear 11 by a connectingmechanism 14. Oxygen is supplied to the breathing mask 10 in a wellknownmanner through a conduit 15.

Disposed between the occipital area of the wearer and the interior ofthe helmet is a resilient or expansible member 16. The resilient member16 is preferably made of foam rubber of the open cell type with a fabric17 adjacent one portion thereof. The fabric 17 is secured to the foamrubber by dipping the resilient member 16 in a rubber bath to form arubber coating 18 around the entire surface of the resilient member.This seals the air within the open cells of the foam rubber but permitsready communication between the various cells to prevent any rupturethereof. Thus, the resilient member 16 is formed with air trapped in theinterior thereof. By securing the portion of the resilient member 16having the fabric -17 secured thereto to the inside of the headgear 11,it is prevented from moving up or down, as viewed in Fig. 1; thus anyexpansion or contraction of the resilient member 16 must occur betweenthe occipital area of the wearer and the headgear 11. Considering theoperation of the present invention, the breathing mask 10 is connectedto the headgear 11 at ground level with the tension of the harnessstraps'12 being sufficient to urge the mask into sealing relationshipwith the face of the wearer; however, the pressure of the mask on theface of the wearer is very slight. As the altitude of the aircraftincreases, the ambient pressure decreases and the trapped air in theresilient member 16 expands. This causes the headgear 11 to movebackwards toward the position shown by the dotted lines of Fig. 1. Sincethe movement of the headgear 11 in the backward direction moves theconnecting mechanism 14, the tension of the harness straps 12 increases.The size of the interior of the resilient member 16 is designed so thatthe tension of the harness straps 12 will always be sufficient, afterthe mask 10 is secured against the face of the wearer at ground levelsufficiently to form a seal therebetween, to maintain a seal between themask and the face of the wearer at any altitude. When the aircraftdescends in altitude, the resilient member 16 contracts since theambient pressure increases and the headgear 11. returns toward its solidline position of Fig. 1. As the headgear 11 moves forward, the tensionof the harness straps 12 reduces but is still sufficient to maintain aseal, between the mask 10 and the face of the wearer.

is made of foam rubber of the closed cell type, instead of the member16. Otherwise, the structure is the same as Fig. -The closed cell typehas air trapped in each of its cells and no rubber coating is necessarybut a fabric 17 is secured to one side of the member 16. The resilientmember 16 is secured to the interior of the headgear llsirnilar to theresilient member 16 by securing the portion of the member 16' having thefabric 17 secured thereto to prevent the member 16' from movingvertical-1y. This causes the expansion and contraction of the. member16' to occur between the occipital area of the wearer and the headgear11.

The movement of the headgear 11 of Fig. 2 is similar to that otf'Fig. 1.Thus, the tension of the harness straps 12 increases through rearwardmovement of the headgear 11 when the altitude increases and decreasesthrough forward movement of the headgear 11 when the altitude decreases.

"The modification of Fig. 3 is similar to Fig. 1 in that the breathingmask is secured to the headgear 11 by the harness straps 12 through theconnecting mechanism 14. Oxygen is supplied to the breathing mask 10,through the conduit 15.

The resilient member'l of. Fig. 1 is replaced in the embodiment of Fig.3 by a hollow resilient member 19, which is preferably'for'rned ofrubber. This member 19 is disposed between the occipital area of thewearer and the interior of the headgear; it is secured to the inside ofthe headgear to insure that its expansion and contraction occur in ahorizontal direction rather than in a vertical direction. The portion ofthe member 19 secured to the headgear hasa fabric 17 secured thereto toprevent damageto the material of the member.

The interiorof the resilient member 19 is connected to the conduit by aconduit'ill so that a portion at the oxygen supplied through the conduit15 to the breathing mask 10 flows into the interior ofthe resilientmember 19. As the ambient pressure decreases'due to the increase inaltitude, the pressure of 'the supply oxygen increases to increase thepressure within the interior of the resilient member 19 to move theheadgear 11 backwards toward its dotted line position of Fig. 1. Thisresults in the connecting mechanism 14 moving rearwardly to increase thetension of the harness straps'12. When the aircraft descends, thepressure of the supply oxygen flowing through the conduit 15 decreases;the combination of the increased ambient pressure and the decreasedoxygen supply pressure within the interior of the resilient member 19causes the resilient member 19 to contract and return the headgear 11toward its solid line position. This, of course, reduces the tension ofthe harness straps 12 in the samemanner as the contraction of theresilient member-16 of" Fig. 1. The size of the resilient member 19 isselected so that the tension of the harness straps 12 is alwayssufiicient to maintain a seal between the mask 10 andthe face of thewearer at any altitude after a seal has been formed at ground level. Theresilient member has an'area approximately the same as the area of theoxygen mask 10 to insure that the compensation of the tension of theharness straps 12 is as desired.

It will be understood that the resilient member 16, 16 or 19 may besecured to the exterior of the headgear 11, if desired. Since therewould be no movement of the headgear 11, it would be necessary to securethe resilient member. to the harness straps whereby the movement of theresilient member would varythe tension of the harness straps to maintainaseal between the mask and the face or" the wearer.

"It will be understood also-that the regulation of the expansion and.contraction of the resilient member may be manual rather than automatic,if desired. For example, a'manual controlled valve could be employedinthe conduit-20 to regulate the oxygen flow therethroug'h to theinterior of-the resilient member 19 whereby'the pressure within themember 19 could'be varied manually.

-Anaadvantage' of this invention is that it providesa more. comfortablefit of the mask at low altitude flying.

Another advantage of this invention is that the pilot is not required tomanually adjust the tension of the mask harness as the altitude varies.A safety factor of this invention is that the automatic adjustment ofthe tension of the mask harness insures that there is no leakage aroundthe mask.

For purpose of exemplification, particular embodiments-oftheinventionhave been shown and described according to the best presentunderstanding thereof. However, it will be apparent that changes andmodifications in the arrangement and construction of the parts thereofmay be resorted to withoutdeparting from the true' spirit and scope ofthe invention.

I claim:

1. In combination, a headgear, a breathing mask, harness meansconnecting the mask to the lower front portion of said headgear, andresilient means affixed to the inside, rearwardmost portion of theheadgear'and adapted to be disposed between the interior of the headgearand the occipital area of the wearer to increase of decreaseautomatically the tension of the harness means as 'the pressurecorrespondingly increases or decreases, said resilient means afiixed' tosaid headgear comprising an open cell foam rubber member and animpervious rubber coating enclosing said foam rubber member so that airis trapped within saidfoam rubber.

2. Incoinbination, a headgear, a breathing mask, harness meansconnecting the mask to the headgear, a resilient memberpositioned infixed relation to the inside of the-headgear and adapted to be disposedbetwee'nithe interior: of the headgear and the occipital area 'of theweareninlet conduit means for supplying oxygen to said breathing-mask,and means to divert to the interiorof the resilient-member a portion ofthe oxygen supplied to said breathing mask by said inlet conduit meanswhereby'the resilient member expands as the oxygen-pressure increaseswhen the ambient pressure decreases to increase the tension of theharness means and vice versa.

3. In combination; a headgear, a breathing mask, harness meansconnecting the mask to the bottom-front portion of said headgear, ahollow resilient member secured interiorly to the lower portion of theheadgear so that the occipital area of the wearer is contacted by saidresilient member, first conduit means attached to said breathing maskandadaptable for delivering a main supply of oxygen thereto, and secondconduit meanslin communication between said first conduit means and theinterior of said hollow resilient member to divert to the interior ofthe resilient member a portion-of the oxygen delivered tothebreathing'mask whereby the resilient member expands as the oxygenpressure increases when the ambient pressure decreases to increase thetension of the harness means and vice versa.

4. A breathing mask for use with a headgear .or the like, r harnessmeans connecting the mask to the lower front portionof said headgear,and a rmilient member affixed to "the interior rear portion ofsaidheadgear and adapted to; be'disposed between the interior of theheadgearrandthe occipital area'of the wearer, a conduit attachcd' to andin eommum'cation with said breathing mask-and adapted to supply oxygenthereto, passage communicating means to divert to the interior of theresilient member .a portion of the oxygen supplied to the, breathingmask by way of said conduit whereby the resilintmerrib'er expands whenthe oxygen pressure increases as the ambient pressure decreases toincrease the tension of the harness means and vice versa.

References Cited in thefile of this patent 1 UNITEDSTATES PATENTS,354,840 Seletz Aug. 1, 194 2,461,364 Ackerman Apr. 19, 1949 1,742,039,Bloom Apr. 17, 195 1, 6 Quilter ot al. NOV. 25, 1,958 2,868,195 FinkenJan. 13, 1959 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTIONPatent No. 2,970,593 February 7, 1961 Henry W. Seeler It is herebycertified'that error appears in the above numbered patent requiringcorrection and that the said Letters Patent should read as correctedbelow.

Column 1, line 34, for "it" read is column 4, lines 20 and 21, for "toincrease of decrease automatically" read to automatically increase ordecrease "a Signed and sealed this 1st day of August 1961,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

